Source: DGNews  |  Posted 2 years ago

By John Otrompke

BOSTON -- December 10, 2009 -- A medical device designed to be implanted in the brain of epileptic patients was well tolerated in a series of more than 700 operations, and reduced the number of partial onset seizures in intractable patients, according to research presented here at the American Epilepsy Society (AES) 63rd Annual Meeting.

The device, approved by the US Food & Drug Administration in 1997, was associated with a 50% or better reduction in partial onset seizures in almost two-thirds of patients.

“The vagus nerve comes from the brain stem and travels to the neck, carrying information out and going to the head and part of the larynx,” said Robert Elliott, MD, New York University Langone Medical Center, New York, New York, speaking here at a podium presentation on December 7. “For some reason, putting a stimulator will use some of the brain’s sensory pathways, and diminish seizure activity.”

The device was approved for treatment of partial-onset epilepsy in patients over 12 years old, but 86 of the 507 consecutive patients in the retrospective study were under 12. While the patients in the study had partial-onset seizures, some of these children suffered from absence epilepsy as well.

The study examined 720 procedures in total; the patients were all considered difficult to treat.

Mean seizure frequency preimplantation was almost 26 per week, while the median was 4 per week. (“One patient had 2,000 seizures per week, and was seizing constantly,” said Dr. Elliott.) Postoperatively, the mean number of seizures dropped to 1.5 per week, while the median number was 12.5 per week. Virtually all of the patients were on antiepilepsy drugs, and there was no decrease in medication requirements associated with the device.

A reduction in seizures of 50% or greater occurred in 66.7% of patients, and 45% of patients experienced at least a 75% reduction in seizures. “In addition, 14% of patients were either seizure-free or had rare, nondisabling partial seizures, such as twitching of the hands,” Dr. Elliott explained.

The therapy was well tolerated. “About 17% of patients had the device removed, and the most common reason for revision surgery was battery replacement,” Dr. Elliott said. “Every 3 to 7 years, you have to change the battery,” he noted.

The most common side effect from implantation of the device was hoarseness. “When the device fires, which could be every couple of minutes, there’s a mild change in the hoarseness of your voice,” Elliott said, pointing out that 1 patient also suffered from vocal-cord paralysis from the surgery.

“We were surprised to find that surrogate markers for more severe epilepsy -- such as the number of failed medications, the number of seizures, or the number who had tried and failed brain surgery -- showed no association with better or worse outcomes,” Dr. Elliott commented.

Presentation title: Vagus Nerve Stimulation for Refractory Epilepsy: Single Surgeon Experience of Over 700 Consecutive Operations. Abstract B.01